The invention relates to a method for the quality assessment of a component produced by means of an additive manufacturing method.
Additive manufacturing methods refer to processes in which material is deposited layer by layer on the basis of digital 3D construction data in order to build up a component generatively by 3D printing. Additive manufacturing methods thus differ from conventional material-removing or primary shaping methods of fabrication. Instead of milling a work piece from a solid block, for example, additive manufacturing methods build up components layer by layer from one or a plurality of materials. Examples of additive manufacturing methods are generative laser sintering or laser melting methods, which, for example, are used for the manufacture of components for aircraft engines. Such a method is already known from DE 10 2004 017 769 B4, for example. In selective laser melting, thin layers of powder of the material or materials used are placed on a construction platform and locally melted and solidified by means of one or a plurality of laser beams. The construction platform is then lowered and another layer of powder is applied and again locally solidified. This cycle is repeated until the finished component is obtained. The finished component can then be further processed as needed or immediately used. In selective laser sintering, the component is produced in a similar way by laser-assisted sintering of powdered materials.
However, laser sintering and melting methods have not been used so far for serial production of components for aircraft engines. In addition, a process permit, a prerequisite of which is the monitoring of diverse process parameters, such as, for example, the laser power as well as the nature and state of the powdered material and the like, is required, in particular, for the use of components that are produced by generative laser methods and are subject to high stresses. In this case, the individual process parameters have to be monitored at intervals in the framework of a process monitoring by means of a respectively adapted, elaborate method of measurement. A method for monitoring layer buildup, which is known as such, is optical tomography, which affords an image for each component layer, the brightness values of which enable conclusions to be drawn about the quality of the additive fabrication process. The quantification of brightness values can be established on the basis of a number of influencing variables, but to date not on absolute values. A good target value process also is subject to different influences, such as, for instance, the component geometry, the loading of the construction platform, the position within the component, etc, and, as a result, can lead to various gray-scale value ranges, which, however, can still characterize a component that has fundamentally good quality.